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The Louis Frost Notes 1685 to 1962
General Remarks on Pictou Coal Field
A cross section of the field shows the Pictou Coal Field to
be highly mineralized, especially in the middle horizon, or the Stellarton
Series. In this series there is 189 feet of coal in 1379 ft. of strata, or
13.7% of the measures are coal.
This abundance of coal is not without its drawbacks. The
seams give off large volumes of gas and are extremely liable to spontaneous combustion. Furthermore, owing to the number and thickness of the
seams and the scarcity of material for packing the wastes, the seams
could only be worked by the caving method and in a descending order, so
that the winning of the coal in this field was attended with unusual
difficulties.
The record of the number of major fires and explosions (see
attached sheet) is an indication of the difficulties of mining
coal in this field, and in at least two of the collieries, the
Allen Shaft and the MacGregor Colliery, fires caused their premature closure before all the coal was recovered, and the balance
that remained could not be recovered economically after the
collieries had been sealed.
In order to effectively cope with the dangers from spontaneous
combustion, it was necessary to work the seams by a panel system,
and the fire stoppings controlling the panels were both numerous
and costly to build.
These stoppings were at one time built by digging keys into
the roof, ribs and pavement until solid ground was reached. This
resulted in stoppings of very large size, in one exceptional
case a stopping was 70 feet high and 26 feet wide. Within past
years it became the practice to trim the roof, ribs and pavement,
build the stopping to a width of five feet with specially prepared
squared blocks 6 ins. by 6 ins. thick laid in cement and, after the
stopping was built, solidify the ground around the stopping by a cementation process. This method, while reducing the cost of building
stoppings, also resulted in a much sounder stopping.
The pioneers in the working of this field, naturally took the
most easily worked coal near the crop, leaving the deeper lying coals
at the bottom of the basin for their successors, who had to contend
with much more difficult working conditions.
Mr. George S. Rice, Chief Mining Engineer of the United States
Bureau of Mines, in a report made on this district to the Department
of Public Works and Mines of the Government of Nova Scotia, stated:
"The changing dip and the numerous faults
taken together with the great thickness of the
individual coal beds centrally in the basin, the
giving off of fire-damp, and the liability of the
coal to fire spontaneously in the workings, make
the most difficult mining conditions I have observed
on this continent."
To overcome some of the difficulties, Mr. Rice proposed that
as the coal was extracted, the waste should be packed hydraulically
with material brought in for this purpose.
With this view the Company officials were in accord, but the
cost of this process was beyond the economic returns available to
render this system workable.
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